US6046453A - Agent identification for anesthetic gas monitors using minimum alveolar concentration (MAC) values - Google Patents
Agent identification for anesthetic gas monitors using minimum alveolar concentration (MAC) values Download PDFInfo
- Publication number
- US6046453A US6046453A US09/042,312 US4231298A US6046453A US 6046453 A US6046453 A US 6046453A US 4231298 A US4231298 A US 4231298A US 6046453 A US6046453 A US 6046453A
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- Prior art keywords
- agent
- anesthetic
- identifying
- gas sample
- primary
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- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 83
- 239000003994 anesthetic gas Substances 0.000 title claims abstract description 20
- 239000003193 general anesthetic agent Substances 0.000 claims abstract description 56
- 238000000034 method Methods 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 31
- 230000001678 irradiating effect Effects 0.000 claims 4
- DPYMFVXJLLWWEU-UHFFFAOYSA-N desflurane Chemical compound FC(F)OC(F)C(F)(F)F DPYMFVXJLLWWEU-UHFFFAOYSA-N 0.000 description 17
- 229960003537 desflurane Drugs 0.000 description 17
- PIWKPBJCKXDKJR-UHFFFAOYSA-N Isoflurane Chemical compound FC(F)OC(Cl)C(F)(F)F PIWKPBJCKXDKJR-UHFFFAOYSA-N 0.000 description 16
- 229960002725 isoflurane Drugs 0.000 description 16
- 230000000241 respiratory effect Effects 0.000 description 9
- 238000012544 monitoring process Methods 0.000 description 7
- 238000002835 absorbance Methods 0.000 description 5
- JPGQOUSTVILISH-UHFFFAOYSA-N enflurane Chemical compound FC(F)OC(F)(F)C(F)Cl JPGQOUSTVILISH-UHFFFAOYSA-N 0.000 description 5
- 229960000305 enflurane Drugs 0.000 description 5
- 229960003132 halothane Drugs 0.000 description 5
- BCQZXOMGPXTTIC-UHFFFAOYSA-N halothane Chemical compound FC(F)(F)C(Cl)Br BCQZXOMGPXTTIC-UHFFFAOYSA-N 0.000 description 5
- 229960002078 sevoflurane Drugs 0.000 description 5
- DFEYYRMXOJXZRJ-UHFFFAOYSA-N sevoflurane Chemical compound FCOC(C(F)(F)F)C(F)(F)F DFEYYRMXOJXZRJ-UHFFFAOYSA-N 0.000 description 5
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000001272 nitrous oxide Substances 0.000 description 2
- 229960001730 nitrous oxide Drugs 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000001225 therapeutic effect Effects 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 1
- 230000003444 anaesthetic effect Effects 0.000 description 1
- 235000013405 beer Nutrition 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
Definitions
- This invention relates to anesthetic gas agent monitors that are used to accurately identify anesthetic agents in a anesthetic gas sample obtained from an anesthetized patient as well as to provide an indication of their relative concentrations.
- an apparatus for measuring the concentration of anesthetic agents in a respiratory gas sample that is inexpensive, simple to use, accurate and fast in its measurements of anesthetic gas concentrations and the identification of the primary and secondary anesthetic agents.
- anesthetic agent monitoring apparatus which operates by measuring the optical transmissivity of a respiratory gas sample at certain wavelengths of light.
- One such anesthetic agent measurement apparatus is disclosed in commonly assigned U.S. Pat. Nos. 5,731,581 and 5,714,759 which disclosures are hereby incorporated by reference.
- the resultant measurements are processed to identify one of the known anesthetic agents that is contained in the gas sample as well as its concentration.
- Infrared anesthetic agent monitoring apparatus generally perform two functions: the identification of the anesthetic agent or agents present in the respiratory gas sample and the determination of the concentration of the identified anesthetic agent or agents. These two functions may be performed either by two separate sets of circuitry in the apparatus or by a common set of circuitry. These apparatus are determined systems, with the number of spectral filters used therein being greater than or equal to the number of anesthetic agents that the apparatus is designed to identify. The selection of the wavelengths passed by the spectral filters is driven by the desire to use wavelengths that are strongly and uniquely absorbed by the anesthetic agents in question.
- an anesthetic agent After an anesthetic agent is identified its identity is displayed to the user along with concentration data. If the user, i.e., the anesthesiologist, changes the anesthetic agent being given to a patient then the two agents must both be identified with one as the primary agent and the other as the secondary agent.
- the primary agent should be the anesthetic which is producing the greatest therapeutic effect or drug response in the patient.
- anesthetic gas measurement apparatus various anesthetic gas agents and the concentration of the agents is identified.
- the identification of primary and secondary agents depends on the number of agents and also the minimum alveolar concentrations (MAC's) for the various agents.
- Minimum alveolar concentrations are the volume concentrations at which fifty percent of the patients are anesthetized.
- the MAC values used in this invention are those for administration of the agent to the patient in conjunction with oxygen.
- the use of MAC information for the identification of primary and secondary agents eliminates instances where a less therapeutic anesthetic agent is first used and the identification of a second more effective anesthetic agent as the primary agent is delayed until the volume concentration of the first agent decreases to a lower level than the second agent. If the MAC of the administered anesthetic agents is taken into consideration instead of only the actual volume concentrations then the second gas will be identified as the primary agent more quickly and accurately.
- FIG. 1 illustrates, in block diagram form, the overall architecture of the automatic gas sample identification apparatus of the present invention
- FIGS. 2 and 2a are a block diagram of the algorithm implemented in the anesthetic gas monitor as part of the invention.
- FIG. 3 is a chart depicting the effect of the present invention on anesthetic agent identification.
- FIG. 1 illustrates in block diagram form the overall system architecture of the apparatus for the automatic identification of gas samples.
- This gas sample identification apparatus 1 functions to both detect the presence and measure the concentration of analytes contained in a gas sample that is passed through a gas chamber 20.
- the anesthetic agent identification means described herein as the preferred embodiment of the invention represents one application of this inventive concept, and the underlying principles behind this identification method is equally applicable to other applications where one or more analytes are contained in a gas sample, and the presence and concentration of these analytes must be determined with accuracy.
- the gas sample identification apparatus 1 is illustrated as including a light source 10, mirrors 13-16, gas chamber 20, detector circuit 30 and computation circuit 40.
- a gas sample is passed through gas chamber 20 while at least one beam of light produced by light source 10 is transmitted through the gas chamber 20 after reflection from mirrors 13-16.
- the gas sample has optical transmissivity characteristics that are determined by the type of components contained in the gas sample as well as their concentrations. Therefore, the light beam that passes through the gas sample in gas chamber 20 is optically processed by various filter and detector elements contained in detector 30 to produce electrical signals that can be used by computation circuit 40 to precisely identify the components contained in the gas sample as well as their relative concentrations.
- respiratory gases obtained from an anesthetized patient are passed through gas chamber 20 to identify the presence and concentration of carbon dioxide (CO 2 ) as well as the presence and concentration of one or more anesthetic agents in the patient's respiratory gases.
- CO 2 carbon dioxide
- the detector circuit 30 and computation circuit 40 must have the capability to measure subtle differences in optical transmissivity in the gas sample to distinguish between the various anesthetic agents and combinations of anesthetic agents used in various concentrations.
- the data received by detector circuit 30 is processed by computation circuit 40 is to obtain a concentration value for one or more anesthetic gas agents present in the gas sample.
- the results of this computation are displayed to the user via a display device 49 which presents an identification of the determined component and its concentration in human readable form, such as an alphanumeric readout.
- FIGS. 2 and 2a are a block diagram which implements an embodiment of the present invention as a software algorithm executed by the computation circuit 40 prior to display of the anesthetic gas concentrations to the user.
- the first step in the post-concentration algorithm is to determine if there has been any anesthetic agent identified by the monitor. If an anesthetic agent has been identified then the elapsed time from initial monitoring must be 15 seconds before continuing with the algorithm as determined in step 110. If an anesthetic agent has not already been identified then the algorithm will continue if the elapsed time from initial monitoring is 5 seconds as determined in step 112.
- steps 115, 120, 125, 130 and 135 the minimum volume concentration threshold of 0.2 v/v % is tested for a 5 second running average for each of desflurane (DES), enflurane (ENF), halothane (HAL), isoflurane (ISO) and sevoflurane (SEVO) respectively and if the minimum volume concentration threshold based on the five second running average is met then the respective flag for each is set in steps 116, 121, 126, 131 and 136.
- a minimum threshold for additional anesthetic agents could be introduced into the algorithm at this point if additional agents become available or widely used.
- the algorithm determines the primary and secondary agents through the use of MAC values. If no agents have been identified as determined by step 140 then the primary agent and the secondary agent are both output to the user on display 49 as "NO AGENT.” If any anesthetic agent has been identified then the algorithm determines if only one agent has been identified at step 150. The only identified agent is then output to the user on display 49 as the primary agent along with the volume concentration data associated with the identified primary agent and the secondary agent is identified as "NO AGENT" in step 151.
- step 160 the minimum alveolar concentration (MAC) values for the agents in oxygen are used in conjunction with the volume concentrations to determine the primary agent which is then output to the user at display 49. For example, if the volume concentration for desflurane is 4 v/v % and the volume concentration for isoflurane is 1.15 v/v % then isoflurane would be identified as the primary agent because it is 100% of its MAC value whereas desflurane is only at 66% of its MAC value.
- the secondary agent is determined in a like manner, i.e., the agent identified having the second higher percentage of its own MAC.
- the MAC values used in the present invention are 6.0 v/v % for desflurane, 1.7 v/v % for enflurane, 0.77 v/v % for halothane, 1.15 v/v % for isoflurane and 1.71 v/v % for sevoflurane.
- the MAC based data is for use of the agent in oxygen.
- a second threshold determination is made for that agent.
- the five second running average of the volume concentration for the secondary agent must be either greater than or equal to 0.3 v/v % or greater than or equal to five percent (5%) of the primary agents five second average volume concentration whichever is greater.
- five percent of the primary agents five second average volume concentration value is computed at step 170.
- the threshold to be used is determined by comparing five percent (5%) of the five second running average of the primary agent to 0.3 v/v %.
- step 180 determines if the threshold has been met by comparing the five second average of the agent with the second highest percentage of MAC with the computed five percent (5%) of the primary agents five second running average. Otherwise in step 190 the five second running average volume concentration for the agent with the second highest percentage of MAC is compared to the 0.3 v/v % threshold. If the appropriate threshold is met then the secondary agent is identified as that agent having the second highest percentage of its own MAC, otherwise the secondary agent is identified as "NO AGENT.”
- FIG. 3 is a graph depicting the data used for agent identification and illustrates the improvement through the use of MAC values.
- DES AVG curve 320 is five second running average for the volume concentration of desflurane which has a MAC of 6.0.
- DES MAC curve 310 depicts the percent of the MAC value of 6.0 which is represented by the respective volume concentration in DES AVG curve 320.
- ISO AVG curve 350 is five second running average of the volume concentration of the anesthetic agent isoflurane which has a MAC value of 1.15 v/v %.
- ISO MAC curve 340 depicts the percent of the MAC value for isoflurane which is represented by the respective volume concentration in ISO AVG curve 350.
Abstract
Description
Claims (11)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US09/042,312 US6046453A (en) | 1998-03-13 | 1998-03-13 | Agent identification for anesthetic gas monitors using minimum alveolar concentration (MAC) values |
Applications Claiming Priority (1)
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US09/042,312 US6046453A (en) | 1998-03-13 | 1998-03-13 | Agent identification for anesthetic gas monitors using minimum alveolar concentration (MAC) values |
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US6046453A true US6046453A (en) | 2000-04-04 |
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US09/042,312 Expired - Lifetime US6046453A (en) | 1998-03-13 | 1998-03-13 | Agent identification for anesthetic gas monitors using minimum alveolar concentration (MAC) values |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030232064A1 (en) * | 2001-10-17 | 2003-12-18 | Burns William H. | Suppression of human activity in an enclosed space |
US20110000488A1 (en) * | 2007-11-12 | 2011-01-06 | Maquet Critical Care Ab | Regulation of delivery of multiple anesthetic agents to a patient from an anesthetic breathing apparatus |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4150670A (en) * | 1977-11-14 | 1979-04-24 | University Patents, Inc. | Anesthesia detector and display apparatus |
US4784486A (en) * | 1987-10-06 | 1988-11-15 | Albion Instruments | Multi-channel molecular gas analysis by laser-activated Raman light scattering |
US4914719A (en) * | 1989-03-10 | 1990-04-03 | Criticare Systems, Inc. | Multiple component gas analyzer |
US5050615A (en) * | 1988-09-02 | 1991-09-24 | Instrumentarium Corp. | Method for the determination of a gas component content in the respiratory gas of a patient |
US5111827A (en) * | 1988-02-11 | 1992-05-12 | Instrumentarium Corp. | Respiratory sampling device |
US5296706A (en) * | 1992-12-02 | 1994-03-22 | Critikon, Inc. | Shutterless mainstream discriminating anesthetic agent analyzer |
US5479019A (en) * | 1993-07-13 | 1995-12-26 | Mic Medical Instrument Corporation | Apparatus for determining the 13 CO2 /12 CO2 ratio of concentrations in a gas sample |
US5714759A (en) * | 1996-02-23 | 1998-02-03 | Ohmeda Inc. | Optical system with an extended, imaged source |
US5731581A (en) * | 1995-03-13 | 1998-03-24 | Ohmeda Inc. | Apparatus for automatic identification of gas samples |
US5800361A (en) * | 1995-02-06 | 1998-09-01 | Ntc Technology Inc. | Non-invasive estimation of arterial blood gases |
-
1998
- 1998-03-13 US US09/042,312 patent/US6046453A/en not_active Expired - Lifetime
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4150670A (en) * | 1977-11-14 | 1979-04-24 | University Patents, Inc. | Anesthesia detector and display apparatus |
US4784486A (en) * | 1987-10-06 | 1988-11-15 | Albion Instruments | Multi-channel molecular gas analysis by laser-activated Raman light scattering |
US5111827A (en) * | 1988-02-11 | 1992-05-12 | Instrumentarium Corp. | Respiratory sampling device |
US5050615A (en) * | 1988-09-02 | 1991-09-24 | Instrumentarium Corp. | Method for the determination of a gas component content in the respiratory gas of a patient |
US4914719A (en) * | 1989-03-10 | 1990-04-03 | Criticare Systems, Inc. | Multiple component gas analyzer |
US5296706A (en) * | 1992-12-02 | 1994-03-22 | Critikon, Inc. | Shutterless mainstream discriminating anesthetic agent analyzer |
US5479019A (en) * | 1993-07-13 | 1995-12-26 | Mic Medical Instrument Corporation | Apparatus for determining the 13 CO2 /12 CO2 ratio of concentrations in a gas sample |
US5800361A (en) * | 1995-02-06 | 1998-09-01 | Ntc Technology Inc. | Non-invasive estimation of arterial blood gases |
US5731581A (en) * | 1995-03-13 | 1998-03-24 | Ohmeda Inc. | Apparatus for automatic identification of gas samples |
US5714759A (en) * | 1996-02-23 | 1998-02-03 | Ohmeda Inc. | Optical system with an extended, imaged source |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030232064A1 (en) * | 2001-10-17 | 2003-12-18 | Burns William H. | Suppression of human activity in an enclosed space |
US20110000488A1 (en) * | 2007-11-12 | 2011-01-06 | Maquet Critical Care Ab | Regulation of delivery of multiple anesthetic agents to a patient from an anesthetic breathing apparatus |
US9095678B2 (en) * | 2007-11-12 | 2015-08-04 | Maquet Critical Care Ab | Regulation of delivery of multiple anesthetic agents to a patient from an anesthetic breathing apparatus |
US20150297857A1 (en) * | 2007-11-12 | 2015-10-22 | Maquet Critical Care Ab | Regulation of delivery of multiple anesthetic agents to a patient from an anesthetic breathing apparatus |
US11141554B2 (en) | 2007-11-12 | 2021-10-12 | Maquet Critical Care Ab | Regulation of delivery of multiple anesthetic agents to a patient from an anesthetic breathing apparatus |
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